1. Field of the Invention
The present invention relates to graft polymers of polymers containing vinyl ester and/or vinyl alcohol units and open-chain N-vinylcarboxamides, processes for their preparation and their use in the production of paper, board and cardboard, as dispersants for pigments and as starch cationization agents.
2. Description of the Background
U.S. Pat. No. 4,880,497 and U.S. Pat. No. 4,978,427 each disclose the production of paper having high dry strength and wet strength, a hydrolyzed copolymer obtainable by copolymerization of N-vinylformamide and ethylenically unsaturated monomers, such as vinyl acetate, vinyl propionate or an alkyl vinyl ether, and hydrolysis of from 30 to 100 mol % of the formyl groups of the copolymer with formation of amino groups being used as a strength agent either on the surface of the paper or in the paper stock prior to sheet formation. The hydrolyzed copolymers are used in amounts of from 0.1 to 5% by weight, based on dry fibers.
EP-A-0 363 319 discloses graft polymers which are obtainable by free radical polymerization of unsubstituted or N-substituted acrylamide or methacrylamide and N-vinyl-substituted amides or vinyl esters of a saturated aliphatic monocarboxylic acid in the presence of adducts of alkylene oxides with a trihydric or polyhydric aliphatic alcohol of 3 to 10 carbon atoms. The graft polymers are used for coloring cellulosic fibers with substantive dyes or reactive dyes as colorants.
U.S. Pat. No. 5,334,287 discloses graft polymers which are obtainable by free radical polymerization of N-vinylcarboxamides, preferably N-vinylformamide, and, if required, other monomers in the presence of monosaccharides, oligosaccharides, polysaccharides or the derivatives thereof in each case and, if required, hydrolysis of the polymerized N-vinylcarboxamido group with formation of vinylamine units. The graft polymers are used as dry and wet strength agents in the production of paper, board and cardboard.
The earlier non-prior-published German Application 19515943.8 relates to graft polymers which are obtainable by free radical polymerization of
(A) monomers or monomer mixtures comprising PA0 (B) polymers which contain at least 3 units of a C.sub.2 -C.sub.4 -alkylene oxide, and/or polytetrahydrofuran in a weight ratio (A):(B) of from 95:5 to 10:90, and subsequent elimination of some or all of the groups ##STR5## from the polymerized monomers (a) of the graft polymer with formation of units of the formula ##STR6## processes for the preparation of the graft polymers and the use of the graft polymers in papermaking as dry and wet strength agents, as fixing agents for interfering substances and dyes, as retention and drainage aids and as promoters in diketene sizing. The graft polymers are furthermore used as starch cationization agents and as dispersants for pigments. PA0 (A) monomers or monomer mixtures comprising PA0 (B) polymers which contain units of vinyl esters of saturated C.sub.1 -C.sub.4 -carboxylic acids and/or vinyl alcohol units, or of mixtures which contain these polymers and polymers having at least 3 alkylene oxide units or polytetrahydrofuran PA0 (A) monomers or monomer mixtures comprising PA0 (B) polymers which contain units of vinyl esters of saturated C.sub.1 -C.sub.4 -carboxylic acids and/or vinyl alcohol units, or of mixtures which contain these polymers and polymers having at least 3 alkylene oxide units or polytetrahydrofuran,
(a) from 10 to 100% by weight of N-vinylcarboxamides of the formula ##STR4## where R.sup.1 and R.sup.2 are each H or C.sub.1 -C.sub.6 -alkyl, (b) from 0 to 90% by weight of other monoethylenically unsaturated monomers copolymerizable with the monomers (a) and PA1 (c) from 0 to 5% by weight of monomers having at least two ethylenically unsaturated, nonconjugated double bonds in the molecule, PA1 (a) from 1 to 100% by weight of N-vinylcarboxamides of the formula ##STR7## where R.sup.1 and R.sup.2 are each H or C.sub.1 -C.sub.6 -alkyl, (b) from 0 to 99% by weight of other monoethylenically unsaturated monomers copolymerizable with the monomers (a) and PA1 (c) from 0 to 5% by weight of monomers having at least two ethylenically unsaturated, nonconjugated double bonds in the molecule, PA1 (a) from 1 to 100% by weight of N-vinylcarboxamides of the formula ##STR10## where R.sup.1 and R.sup.2 are each H or C.sub.1 -C.sub.6 -alkyl, (b) from 0 to 90% by weight of other carboxyl-free monoethylenically unsaturated monomers copolymerizable with the monomers (a) and PA1 (c) from 0 to 5% by weight of monomers having at least two ethylenically unsaturated, nonconjugated double bonds in the molecule PA1 (1) the polymers described above and containing vinyl ester and/or vinyl alcohol units and PA1 (2) polymers having at least 3 alkylene oxide units or polytetrahydrofuran. PA1 (a) from 1 to 99% by weight of N-vinylformamide and PA1 (b) from 99 to 1% by weight of vinyl formate and/or vinyl acetate
in the presence of